In some instances, a wireless device may be required to send a message that has been scheduled for transmission. Such messages may be scheduled synchronisation messages, which are transmitted on a scheduled basis for synchronising information between the wireless device and another node. Such messages are ideally transmitted according to a scheduled time, but may be transmitted earlier.
In other instances, a wireless device may be required to acknowledge receipt of a packet. Such acknowledgement takes form of an acknowledgement message sent from the wireless device to the network. When the network receives the acknowledgement message, the network is provided with a confirmation that the wireless device has received the packet. In absence of such confirmation by a predetermined time after sending the data packet, the network assumes that the wireless device did not receive the packet and will re-send the packet. An acknowledgement message may acknowledge receipt of more than one received packet. Waiting before sending an acknowledgement message may allow additional received packets to be acknowledged by a single acknowledgement message.
Packet communication to and from the wireless device is done so over a communication channel. If a wireless device is to transmit a packet, and its communication channel has been torn down, then the wireless device re-establishes the communication channel to transmit the packet. Re-establishing the communication channel consumes resources. First, establishing the communication channel consumes network resources. Second, establishing the communication channel consumes battery power of the wireless device. Third, establishing the communication channel requires time.